The present invention relates to a portable power working machine, such as a chain saw, a brush cutter, a hedge trimmer, and the like, in which the working components are driven by an internal combustion engine. In particular, the present invention relates to a portable power working machine that is constructed to prevent as much as possible an air cleaner attached to an air intake system of the internal combustion engine from becoming clogged with dust.
A conventional portable power working machine, such as a chain saw, generally has a small air-cooled internal combustion engine for driving the working components, such as a saw chain. The engine is mounted in a main housing. A cooling fan driven by the internal combustion engine is disposed on one side of the main housing. A carburetor chamber containing an air cleaner and a carburetor is mounted on an upper rear side of the internal combustion engine.
In the operation of a portable power working machine of the type described above, dust that includes sawdust of relatively large size, powder of cut material and sand-like dust are inevitably generated. When dust of those kinds is allowed to enter together with air into the air intake system of the internal combustion engine and to collect on the filter element of the air cleaner, clogging of the filter results. Clogging causes irregularities in the operation of the engine as well as a deterioration in the performance of the engine due to an insufficiency in the flow rate of intake air. Accordingly, it is required in the operation of the portable power working machine to frequently clean the air cleaner, which is a task that is quite troublesome for the operator.